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https://github.com/zhigang1992/react-native.git
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Refactor JS touch dispatch from ReactRootView
Reviewed By: andreicoman11 Differential Revision: D3035589 fb-gh-sync-id: a4af7b0be89e5ea13367481697ff4b3dda8536b1 shipit-source-id: a4af7b0be89e5ea13367481697ff4b3dda8536b1
This commit is contained in:
Dave Miller
committed by
Facebook Github Bot 4
Facebook Github Bot 4
parent
e674e45c2e
commit
39fdce259d
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/**
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* Copyright (c) 2015-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*/
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package com.facebook.react.uimanager;
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import android.view.MotionEvent;
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import android.view.ViewGroup;
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import com.facebook.common.logging.FLog;
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import com.facebook.infer.annotation.Assertions;
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import com.facebook.react.common.ReactConstants;
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import com.facebook.react.common.SystemClock;
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import com.facebook.react.uimanager.events.EventDispatcher;
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import com.facebook.react.uimanager.events.TouchEvent;
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import com.facebook.react.uimanager.events.TouchEventType;
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/**
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* JSTouchDispatcher handles dispatching touches to JS from RootViews. If you implement RootView
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* you need to call handleTouchEvent from onTouchEvent and onInterceptTouchEvent. It will correctly
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* find the right view to handle the touch and also dispatch the appropriate event to JS
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*/
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public class JSTouchDispatcher {
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private int mTargetTag = -1;
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private final float[] mTargetCoordinates = new float[2];
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private boolean mChildIsHandlingNativeGesture = false;
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private final ViewGroup mRootViewGroup;
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public JSTouchDispatcher(ViewGroup viewGroup) {
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mRootViewGroup = viewGroup;
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}
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public void onChildStartedNativeGesture(MotionEvent androidEvent, EventDispatcher eventDispatcher) {
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if (mChildIsHandlingNativeGesture) {
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// This means we previously had another child start handling this native gesture and now a
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// different native parent of that child has decided to intercept the touch stream and handle
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// the gesture itself. Example where this can happen: HorizontalScrollView in a ScrollView.
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return;
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}
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dispatchCancelEvent(androidEvent, eventDispatcher);
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mChildIsHandlingNativeGesture = true;
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mTargetTag = -1;
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}
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/**
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* Main catalyst view is responsible for collecting and sending touch events to JS. This method
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* reacts for an incoming android native touch events ({@link MotionEvent}) and calls into
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* {@link com.facebook.react.uimanager.events.EventDispatcher} when appropriate.
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* It uses {@link com.facebook.react.uimanager.TouchTargetHelper#findTouchTargetView}
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* helper method for figuring out a react view ID in the case of ACTION_DOWN
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* event (when the gesture starts).
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*/
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public void handleTouchEvent(MotionEvent ev, EventDispatcher eventDispatcher) {
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int action = ev.getAction() & MotionEvent.ACTION_MASK;
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if (action == MotionEvent.ACTION_DOWN) {
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if (mTargetTag != -1) {
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FLog.e(
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ReactConstants.TAG,
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"Got DOWN touch before receiving UP or CANCEL from last gesture");
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}
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// First event for this gesture. We expect tag to be set to -1, and we use helper method
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// {@link #findTargetTagForTouch} to find react view ID that will be responsible for handling
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// this gesture
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mChildIsHandlingNativeGesture = false;
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mTargetTag = TouchTargetHelper.findTargetTagAndCoordinatesForTouch(
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ev.getX(),
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ev.getY(),
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mRootViewGroup,
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mTargetCoordinates);
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eventDispatcher.dispatchEvent(
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TouchEvent.obtain(
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mTargetTag,
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SystemClock.nanoTime(),
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TouchEventType.START,
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ev,
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mTargetCoordinates[0],
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mTargetCoordinates[1]));
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} else if (mChildIsHandlingNativeGesture) {
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// If the touch was intercepted by a child, we've already sent a cancel event to JS for this
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// gesture, so we shouldn't send any more touches related to it.
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return;
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} else if (mTargetTag == -1) {
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// All the subsequent action types are expected to be called after ACTION_DOWN thus target
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// is supposed to be set for them.
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FLog.e(
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ReactConstants.TAG,
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"Unexpected state: received touch event but didn't get starting ACTION_DOWN for this " +
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"gesture before");
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} else if (action == MotionEvent.ACTION_UP) {
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// End of the gesture. We reset target tag to -1 and expect no further event associated with
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// this gesture.
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eventDispatcher.dispatchEvent(
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TouchEvent.obtain(
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mTargetTag,
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SystemClock.nanoTime(),
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TouchEventType.END,
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ev,
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mTargetCoordinates[0],
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mTargetCoordinates[1]));
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mTargetTag = -1;
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} else if (action == MotionEvent.ACTION_MOVE) {
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// Update pointer position for current gesture
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eventDispatcher.dispatchEvent(
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TouchEvent.obtain(
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mTargetTag,
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SystemClock.nanoTime(),
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TouchEventType.MOVE,
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ev,
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mTargetCoordinates[0],
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mTargetCoordinates[1]));
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} else if (action == MotionEvent.ACTION_POINTER_DOWN) {
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// New pointer goes down, this can only happen after ACTION_DOWN is sent for the first pointer
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eventDispatcher.dispatchEvent(
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TouchEvent.obtain(
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mTargetTag,
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SystemClock.nanoTime(),
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TouchEventType.START,
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ev,
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mTargetCoordinates[0],
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mTargetCoordinates[1]));
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} else if (action == MotionEvent.ACTION_POINTER_UP) {
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// Exactly onw of the pointers goes up
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eventDispatcher.dispatchEvent(
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TouchEvent.obtain(
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mTargetTag,
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SystemClock.nanoTime(),
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TouchEventType.END,
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ev,
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mTargetCoordinates[0],
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mTargetCoordinates[1]));
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} else if (action == MotionEvent.ACTION_CANCEL) {
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dispatchCancelEvent(ev, eventDispatcher);
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mTargetTag = -1;
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} else {
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FLog.w(
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ReactConstants.TAG,
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"Warning : touch event was ignored. Action=" + action + " Target=" + mTargetTag);
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}
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}
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private void dispatchCancelEvent(MotionEvent androidEvent, EventDispatcher eventDispatcher) {
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// This means the gesture has already ended, via some other CANCEL or UP event. This is not
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// expected to happen very often as it would mean some child View has decided to intercept the
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// touch stream and start a native gesture only upon receiving the UP/CANCEL event.
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if (mTargetTag == -1) {
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FLog.w(
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ReactConstants.TAG,
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"Can't cancel already finished gesture. Is a child View trying to start a gesture from " +
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"an UP/CANCEL event?");
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return;
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}
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Assertions.assertCondition(
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!mChildIsHandlingNativeGesture,
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"Expected to not have already sent a cancel for this gesture");
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Assertions.assertNotNull(eventDispatcher).dispatchEvent(
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TouchEvent.obtain(
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mTargetTag,
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SystemClock.nanoTime(),
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TouchEventType.CANCEL,
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androidEvent,
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mTargetCoordinates[0],
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mTargetCoordinates[1]));
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}
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}
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